A few days ago, at the conservative Illinois Review, an unnamed author who I assume is editor Fran Eaton got excited about some basic science in a post titled "Biology Textbook Author Asserts Life Begins at Conception":

When does life begin?  At conception?  When the fertilized egg begins to multiply cells?  When the zygote embeds itself into its source of nutrition?

A growing number of scientists are beginning to assert that life can begin nowhere else but at conception, because at the moment when an egg is fertilized, it is either a human, a squirrel, an elephant or a dog. At that moment on, then, is when human life should be protected from planned destruction.

Actually, this is not some new trend that is getting support from "a growing number of scientists." I'm pretty sure that biologists have never disputed the fact that fertilized eggs are alive -- at least not since 1651, when William Harvey figured out that all animals, including humans, come from eggs -- nor is there any doubt that a fertilized egg is of the same species as its parents. Fertilized human eggs have been human life since as long as scientists have known where babies come from.

In referring to an article at LifeNews.com by biologist Gerard Nadal, Eaton describes it as reporting Professor Scott Gilbert's "findings." But the quote is from the 9th edition of Gilbert's Developmental Biology, which is one of the standard textbooks in the field. I doubt that Gilbert is reporting any novel findings.

Here is the quote:

Traditional ways of classifying catalog animals according to their adult structure. But, as J. T. Bonner (1965) pointed out, this is a very artificial method, because what we consider an individual is usually just a brief slice of its life cycle. When we consider a dog, for instance, we usually picture an adult. But the dog is a "dog" from the moment of fertilization of a dog egg by a dog sperm. It remains a dog even as a senescent dying hound. Therefore, the dog is actually the entire life cycle of the animal, from fertilization through death.

I don't have a copy of the book handy, but that doesn't sound like a scientific conclusion. Rather, it sounds like a scientific definition. It sounds like Gilbert is describing what his book is about, and why it is an important field of study. He's making the point that a thorough scientific study of life isn't only about what an organism is, it's also about the changes that organism underwent to become what it is.

Eaton finishes with this conclusion:

Gilbert says a dog's life begins at fertilization and ends at that dog's death. How soon can we expect him and other scientists to define a human's life cycle the same?

I think that's backwards. Dr. Nadal was't quoting Gilbert's book as evidence that scientists have changed their minds, he was using the quoted passage to show that his own pro-life position is based on science that is so widely accepted it's in a textbook. Here's part of Nadal's conclusion:

We are human for our entire life cycle. We are whole and complete in form and function at every stage of our development, for that given developmental stage. The prepubescent child is fully human, even though they lack the capacity to execute all human functions, such as abstract reasoning, or reproduction.

In the same way, the early embryo is alive and fully human, though it has not yet executed all human organismal functions.

Except for the overloaded use of the word "fully," that's certainly how I'd expect a biologist to see it, especially a developmental biologist who studies organisms' entire life cycles. I really don't think it's a controversial idea. Eaton is missing the point if she thinks this is some new breakthrough. No one seriously doubts that fertilized eggs are human life.

Or so I thought. You see, just to be sure, I decided to do a little Googling, which lead to the National Abortion Rights Action League's answer to the question:

DOESN'T LIFE BEGIN AT CONCEPTION?

That's a question each person must decide for him- or herself. These issues involve matters of personal, moral, religious, and scientific beliefs. This is an area where politicians should have no role.

Here NARAL is using the word "life" to mean something more than just biological life. That's not exactly unjustified -- there's plenty of etymological support -- but it seems to me they're evading the question.

The Pro-Choice Action Network also has an evasive answer to the same question:

There is no scientific consensus as to when human life begins. It is a matter of philosophic opinion or religious belief. Human life is a continuum---sperm and eggs are also alive, and represent potential human beings, but virtually all sperm and eggs are wasted.

This is technically true, and I think it's the same point Nadal was making in his article. Human life doesn't begin at birth. It doesn't even begin at conception. The unfertilized human egg was alive, and it came from a woman who was alive, and she grew from a living egg, which came from a living woman...and so on, going back maybe 100,000 generations until you reach the predecessor species from which humans evolved. Human life extends back continuously over millions of years.

But that's not what people mean when they ask, in the context of the abortion debate, "Does life begin at conception?" That's because they're not really asking the right question.

Professor Scott Gilbert has been out of the office, but he found the time to dash off a quick note when I asked him to comment:

Thanks for sending this on. One can't help people taking quotations out of context. Creationists do it all the time. We also call a human a human when that person is dead, even if they are not a person anymore. We don't eat humans, we bury them. But the dead can't vote or inherit. So calling a dog a dog even as a zygote is kind of obvious. Even a dog sperm is a dog sperm and not a human sperm. But (unless your a Monty Python fan), that don't make the sperm a person.

(Professor Gilbert also suggests reading an op-ed he wrote for the Philadelphia Inquirer.)

Nadal stumbles into this when he argues that we consider both prepubescent children and embryos to be human life, even if neither is capable of performing all human functions. He's right on the biology of course, fertilized human eggs are human life, but he's not properly addressing the moral issue, because when it comes to morality, function matters.

Here in the United States, the legal and clinical definitions of death are specified in terms of brain activity. A person's body can be kept alive by machines, and that's certainly human life -- blood is still flowing, the metabolism is still processing nutrients -- but if the brain has irreversibly ceased to function, we pronouce the person dead.

Or consider that having consensual sex with an adult is not generally considered an immoral act, but having consensual sex with child is a crime. The reason we make this moral distinction is because even though a child is fully human, we don't believe they have the mental function to make decisions about their sexuality.

Similarly, a person's rights depend on their behavior, which is another aspect of how they function. Obey the law, and you remain free. Rob a bank, and you go to jail. Try to kill someone, and you can be killed in self-defense, or executed after a trial.

The rights we grant people, and the respect we show to them, do not depend solely on the scientific fact that they are human life. We usually make the distinction by discussing not when a fertilized egg develops into human life, but when it becomes a person. That's a harder question, and one that science can inform but not fully answer.